Manufacture of phonograph records



Patented Apr. 29, 1941 James H. Hunter, Lansdowne, Pa... assignor I toRadio Corporation of America, acorporation of Delaware No Drawing.Application June 30, 1937,

Serial No. 151,312

3 Claims. (01. 204-5) This invention relates to the phonograph recordart, and more particularly to a method of preparing recording waxes forthe electro-deposition of a metallic coating thereon which, whenstripped from the wax, constitutes a master matrix.

In the production of phonograph-records, after the original recordinghas been made in a wax blank, the wax record is coated with a metalizingpowder and subsequently electro-plated with a suitable metallic depositwhich, after being removed from the wax and bacl-zed up by a copper or'other metal backing. serves as the master matrix. The metalizing powderisnecessary in order to make the surface of the wax electroconductive.Up to the present. time, various metalizing powders have been used inmaking to be understood that the percentage of fatty acid.

added to the metalizing powder is merely illustrative and not in any waylimiting. Since the specific tack producing material employed and thequantity thereof may be varied over a wide range, I desire that myinvention shall not be limited except insofar as is made necessary bythe priorart and by the spirit of the appended the surface of the wax orother similar non-conclaims. ductive body conductive, and all of them,so far I claim as my invention: as I am aware, have depended solely onthe tacki- 1. The method of forming a phonograph record ness of the bodytohold the powder to the surface thereof. Inasmuch as the tackiness ofthe wax varies greatly with temperature, being re duced considerablywhen the wax is cold, reliance solely upon the tackiness of the waxconstituted a great disadvantage.

The primary object of my invention is to pro vide an improved method ofapplying the electroconductive powder to the surface of the wax to causethe same to adhere thereto.

7 More specifically, it is an object of my inven-' tion to provide animproved metalizing powder which will adhere strongly to the surfaceofthe wax record regardless of the temperature thereof. I have found. inaccordance with my invention. that by the addition of every small amountof a fatty acid, such as stearic acid, oleic acid, lard or similarmaterials. to the metalizing powder, the adhesion thereof to therecording wax is greatly improved, and this results in an improvement inthe electro-depositing operation.

matrix which comprises preparing an original wax phonograph record.applying to said wax record a conductive powder having incorporatedtherein approximately 0.1 percent by weight of a fatty compositionselected from the group consisting of stearic acid, oleic acid and lard,electrodepositing a layer of metal over said powder, and finallyseparating said v electrodeposited metal layer from said wax record. Y

s 2. The method of forming a phonograph record matrix which comprisespreparing an original wax phonograph record, applying to said wax recorda conductive powder having incorporated therein stearic acid in anamount of approximately I have also found that even when a small amountI therein stearic acid in an amount of "approxiof tack producingmaterial is incorporated with the metalizing powder the difficultiesexperienced in cold weatherare no longer encountered. As

an example of the effectiveness of my improved metaliaing powder, I havefound that the addition of approximately 0.1% by weight ofstearic 0.1percent by weight, electrodepositing a layer of metal over said powder,and finally separating said electrodeposited metal layer from said waxrecord.

1 g 3. The method of forming a phonograph record matrix which comprisespreparing an original wax phonograph record-applying'to said wax recordpowdered bronze having incorporatedmately 0.1 percent by weight,eiectrodepositing a layer of metal over said powder, and finallyseparating said electrodeposited metal layer from said

